Derivative Financial Instruments (Location And Amounts Of Pre-Tax Gains (Losses) On Cash Flow Hedge Derivatives Financial Instruments) (Details) - Cash Flow Hedging [Member] - Designated as Hedging Instrument [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Net Gains and (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (effective portion)	$ (4)	$ 35
Cost Of Revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Gains and (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (effective portion)	(3)	30
Selling, General and Administrative Expenses [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Gains and (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (effective portion)	(1)	5
Foreign Exchange Forward [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Derivative Gains/Losses Recognized in Accumulated Other Comprehensive Income (Loss) (effective portion)	$ 39	$ (14)